@DB1 

try this

function openinc() {

    if(confirm('Are you sure you would like to proceed?'))
        gsftSubmit(null, g_form.getFormElement(), 'transfer_incident');
    else
     return;
}

if (typeof window == 'undefined')
    runBusRuleCode();

//Server-side function
function runBusRuleCode() {

    var ritmTable = current.getTableName();
    var ritmSysID = current.getUniqueValue();
    var ritmNum = current.getValue('number');
    var comments = 'Incident created from ' + ritmNum;

    var inc = new GlideRecord("incident");

    inc.caller_id = current.request.requested_for;
    //inc.assignment_group = assignmentGroup;
    inc.short_description = current.short_description;
    inc.cmdb_ci = current.cmdb_ci;
    inc.assignment_group = current.assignment_group;
    inc.business_service = current.business_service;
    inc.impact = current.impact;
    inc.urgency = current.urgency;
    inc.description = current.variables.description;
    inc.comments = comments;
    inc.parent = ritmSysID;
    var incSysID = inc.insert();
    var incTable = inc.getTableName();
    var incNum = inc.getValue('number');
    GlideSysAttachment.copy(ritmTable, ritmSysID, incTable, incSysID);
    current.comments = 'RITM converted to  ' + incNum + '. Please use this reference from now on.';
    current.setValue('state', '10');
    gs.addInfoMessage(gs.getMessage("Incident {0} created", incNum));
    action.setRedirectURL(inc);
}

If my response helped please mark it correct and close the thread so that it benefits future readers.